Centrifugal fluid moving apparatus



June 15, 1937. H. F. HAGEN CENTRIFUGAL FLUID MOVING APPARATUS Original Filed July 5, 1934 4 Sheds-Sheet 1 c I. V l I 1 Invenibr' Harold IfHagen Juhe 15, 1937. v HAGEN Rt:- 20,409

CENTRIFUGAL FLUID MOVING APPARATUS Original Filed Jul 5, 1934 4 Sheets-Sheet 2 1310677272)? 19207051711 Hagen wfifiorfleg June 15, 1937. H. F. HAGEN CENTRIFUGAL FLUID MOVING APPARATUS Original Filed July 5, 1934 4 Sheets-Sheet 3 8N1] Nu fi 2 r. R LI. we MN m b n H H N 4 .III III IN 0 v I H HHM HH m QM. QN w b N. 0 an wn N. K m w llll i L w an h 2L wfimww l ver l'zor June 15, HAGEN. 'CENTRIFUGAL FLUID MOVING APPARATUS 7 Original Filed July 5, 1934 4 Sheets-Sheet 4 Reisaued June 15, 1931 v 20,409.

UNIT-ED sr 'rEs PATENT OFFICE CENTRIFUGAL FLUID MOVING APPARATUS Harold F. Hagen, Dedham, Masa, assignor to B. F. Sturtevantflompany, Inc., Hyde Park, Boston, Mass.

Original No. 2,004,516, dated June 11, 1935, Serial No. 733,783, July 5, 1934. Application for reissue September 11, 1936, Serial No. 100,315

.25 Claims. (Cl. 230-134) This invention relates to apparatus for the sucoutlet is designed to emciently turn the air tion or compression of fluids, and relates more Without the usual noise. x particularly to fans or blowers for moving air or According to a feature ofthis invention, the other gases. radial type fan blades are provided with cln'ved A fan' or blower, according to this invention, portions at their entering edges, which extend employs a casing having the logarithmic spiral into the air inlet zone, and which are so curved outline generally used in fan design, but the as to receive and direct just sumcient of the air present fa'nis novel in that the air inlet, the fan entering the fan onto the main working area of blades, and the air outlet are designed to give the radial blades and completely load same with maximum efliciency with minimum noise, andv to smoothly flowing air, with minimum turbulence m possess maximum strength in a unit occupying and minimum resistance of movement. In one, a minimum of space, and being capable of opand the preferred embodiment of the invention, erating under heavy loading at very high speeds. the curvedportions of the blades are formed with l Since it is desired to provide a high speed fan, conoidal surfaces, all elements of which are a plurality of radial type blades are selected to straight and parallel to a plane perpendicular 15 carry the-main gas load With this type of to the center line of the rotary shaft of the tan, blade, the centrifugal forces on the blades are and which, if extended, would touch the center a minimum and the fan may be operated at high line of the shaft. Not only can the straight and speeds without danger of blade collapse. curved portions of this shaped blade be easily 2 According to this invention, every element of laid out by a pattern maker, and easily and 2 0 the fan is designed to provide for the potential cheaply formed in the shop, but due to the fact flow of air. The potential flow may be described t at all portions of the blades extend in lines as the flow, free from all internal eddy currents radiating from the c line 0! the Shaft, the that the air would take into, through, and out of blades are under minimum strain due to centhe fan under the action of all the forces acting trifu forces- 5 upon it. The present fan is designed from inlet, Acc d ng to anO he fe t e 0 e inVentiDn. through the fan, to the outlet for smooth air t e curved portions of the blades are connected flow and without production of eddy currents at their outer peripheries with a shroud ring which consume power and cause inefilciency and which a s inner Surface st am ed t0 Provide noise. a smooth airflow, without eddy currents, from 30 In the ordinary fan, an inlet is provided, which the inlet side of the casing to the outer periphery not only usually provides insumcient air to prop- 0 t e Whee ed by the plurality erly load the fan blades, but the contours of the blades. .The shape of the shroud ri a d t e inlet, the casing, the fan wheel, and the blades proportions of the a P 8 through the Wheel are usually such that substantial eddy currents e n c d c w e req c D occur at. every transfer of the air from on tential air-flow. working portion of the fan to the other, and at The above described features of the invention every slight change of direction of the air. enable a r e ai in et. equal in size t the As will be brou ht ut in th following descflptive wheel diameter to-be employed, with smooth 40 tion, fan .a'ccordjng to this invention is and even distribution of entering air to the wheel, 40 vided with an inlet which has sumcient area and 3 a l s? g g the f g g fi 232: .eprouconoe ycurrens i 3, ,gffifififigififigjg: of air flow, with the result that the entering air designed cooperate with the Inlet and to is fed into the wheel and onto the working edges vide potential air now. The inlet casing and the the blades .mhwt and with minimum 45 v noise, and with resulting eflicient operation i g i z g g f the According to another feature of the invention, F Y 'theairinlettothewheel isintheformof ai'rusents without usual, noisetrum of a hollow cone, the lower, or larger, base of edge of each fan blade is designed to pick up the fr t being located wheat from the no the entering t -flw h interruptmn wheel, andhavinga diameter largerthan that of of the potential alr flow. and to direct just sufllth h l, th r, o alle base or the fruscient air, and no more; in potential flow, to load trum terminating just inside the outermost edge the radial surface of its respective blade. -I1keof the'streamlined' ring, which is attached to the a wise, thecut-off sheet associated with the fan periphery at the curved portions of the blades.

directtheenteringairsmoothlyandwlthmini- 11mm resistance upon the radial working oi'theblades. v Another object or the'invention is to provide -aradialtypehnblade,havingacurvedentering 35eige,withaconoid||.lsurface.

Another object o! the invention. is to enclose mecunededgeaorapmamyoxndialtwerm bladeswlthinaahroudrinmtheinnersurfoceot whichisstreamlinedtomostetmientlydirectthe enteringairontothefanblades. V

Anothu'objectoitheinventionistoprovidea fan having a plurality o! radial blades. with curvedenteringedgegwithaconicalairinlet.

I Anotherobiectoi'thelnvenflonistopmvidea fanbavingaphiralityoi'radialbladeswithcurved enteringedgemwithanairinlethavingalarger diameterattheedeeotthecasingmostremote wlromthefanbladesthanthatolthelanwheel Anotheroblect otthe invention isto acnt-oflsheetintheoufletareaotthecuingo! ahmwhicheliminateatheseriesofaifletndses producedbytheianblades.

.ammuobiectatn mmumnto' atanwhiehis'soimm .let. Such ofH:.1-uponacylindertoionnaconoidal Fig.3isanelevationviewota1anbladeproduced from a pattern, as shown bvFig. 2, and modified for attachment to the shaft of the tan:

Pig. 4 iso developed view or the blade of Fig. 3; Fla. isaproiectedviewoithebladeoil'lg. 3;

Fix. a n a sectional view taken along the lines mg. a;

H3. 9 is a sectional view taken along the lines is I sectional view taken along the lines 3; is sectional view taken along the lines evation view looking toward the end of the blade of Fig. 3;

I13. '13 is a view showing several of the blades invention;

. Fig. 14 is an end view looking into the inlet of a tan with blades having curved inlet portions with substantially conoidal surfaces, according to this invention:

Fig. 15 is a sectional view taken along the lines li-ll oi the fan 01' Hz. 14;

Pig. 16 is a sectional view taken along the lines "-48 or l5;

Indesinningtheianaccordingtothisinvention,itwnsdecidedtoprovidethe enteringedges &

air-to be acted upon by each blade, melon contact withthe entire radial working surface of theblade,insmooth airflowwlthout the productionofturbnlenceotairflow. Itisrealimedthat beenpmposedtopiovideradial has been to combine propeller ru tim blades. the Pr p ller Wil blmhsprovidimambstantialportionofthetotal efiectiveworkingarea-ot theian. Buchanamoment is disclosed in U. 8. Patent No. 430,-

'l. isued June 34, 1890, to H. H. Barclay. with nchtypepriorthepropellerporflonsotthehladesforcedtheenteringairyat highvelocity.mtothecenter oi'thetnn wheel. where later it, ,jip'onthe flat-races ot the .bnthslmplytotak etheenteringair similartoHgJinse'rtedinplace'ontheahaftand withinthecasingotatamaccordingtothis.

iorthepurposeof'directingsmoot hlytheentebwhichthtertobeworkeduponbytheflatwmt- 1s ing area of the respective blade, and to direct and confine this portion of the entering airin potential flow along a course which brlngs'the air into smooth contact with the flat working area of the blade and without the production of eddy currents. Only sumcient entering air is drawn. in and directed by the curved entering edge of each blade as, to sufficiently load the flat surface of its respective blade, and the contour of the entering edge is so chosen that in its relation to the remainder of the blade, the entering air is given no greater directional kinetic energy on its way to meet the working area of the blade than is necessary for placing it into complete contact with the mathematically and experimentally, does not,

Oil

however, take the direction shown by the vector Vr, and it would be undesirable that it do so, since if it did, it would impact sharply against the onwardly moving radial blade surface. Mathematical calculations and experimental data 'have shown that a curved inlet edge for a radial blade was desired, and for the blade having the flat or radial portion B, the curved portion-C was selected as a suitable curve for the inlet edge,

inasmuch as it was determined that the entering air, .if it followed the outline C for the purpose of being directed against the working area B, would tend to follow this curve in potential flow, as the normal one it would take under the various forces acting upon it,

The outiineof the blade shown by Fig. 1 is a plan view looking downwardly upon the top of the blade. The'curved portion C and the straightportion B are the portions at the outermost extremity of the blade. Since theblade andairvelocities decrease toward the center of the blade, obviously the curved inlet portion of the blade should have a shape which varies according to its distance from the axis of rotation. While, under practical operating conditions, a given radius of curvature of the curved inlet portion could possibly be maintained the entire diameter of the blade, it would be difllcult in the shop to construct such a blade because of the necessity for attaching the innermost portion of the blade to the Y shaft.

A study of the preferred form of the blade, taking into consideration both its maximum performance in operation and the ease and cost of manufacture in the shop, established that if the curved inlet portions were made to have a'surface of a conoid, every desirable factor would bepresent,-this because the inlet portion would change in curvature from the shaft'to the periphery of the wheel, and also because the blade parallel to a given plane. I

Referring now to Fig. 2, theblade, of Which- Fig. l is a plan view. is shown developedto have its curved entering edge as a surface of a conoid. The shaft to which the blade is to be attached is indicated by D, and the shaft has the center line indicated by c-,i. In order to provide the curved inlet edge in the surface of a conoid, it is necessary to project the outer curve B, C upon the outer surface of a'cylinder. So, with reference to Fig. 2, the upper left hand portion of the geometrical diagram illustrates a plan view of the blade outline projected upon its cylinder, looking downwardly upon the cylinder; the lower left hand corner illustrates a profile view, looking towards the end of the -conoldal surface so formed, and the lower right hand corner illustrates an end view, looking towards the side of the cylinder.

It will be noted, with reference to Fig. 2, that all elements of the curved portion of the blade, regardless of their distance from the center, are in straight lines radiating from the center of the axis D. The radial lines shown in the lower left hand corner'of Fig. 2 are the generatices and it is seen that they all radiate from the center of the shaft. In the lower right hand corner of Fig. 2, the same generatices are seen to be parallel to each other and to touch the center line of the shaft. 4

The blade with itsconoidal inlet surface, as-

determined by Fig. 2, is modified, as shown by Figs. 3 to 13, for installation in an actual fan. A portion along the line 20 is removed to provide a clearance for the inner edge of the inlet cone II. The blade is arranged to be bent along the dotted lines Hand a portion along the line 23 is removed to permit the blade to be fastened to the back plate 24 (Fig. 13). The blades are also provided with the recessed portions 25, which receive the lower portion of 'the streamlined shroud ring 29 (Fig. 13). Otherwise, the blades are shaped substantially as shown by Fig. 2, and this shape may perhaps be more easily understood with reference to Figs. 3 to 12 inclusive, which show sectional views along different lines, and

projected and end views of the blade.

Referring now to Figs; 14 to 17 inclusive, one embodiment of an assembled fan, according to this invention, will be described. The plurality of blades indicated generally by 21 are firmly attached, as by welding, to the hub 28 and the back plate 24. The curved portions C of the blades are welded to'the streamiinedring 29, the straight or flat portions B of the blades having no enclosing ring so that the air is free to flow past their- I outer ends.

The inlet portion of the casing, indicated generally by 30, is shaped, .as has previously been Y explained. as the frustrum of a hollow cone, 'the larger, or outer, base 3| having a larger diameter than that of the fan wheel, and the inner, or small, base 32 having a diameter substantially equal to that of the fan wheel. The innermost ends 2| of the inlet cone terminate just beneath the outermost'portion of the streamlined ring 29. It has previously been explained just how the curved inlet portions of the blades have been so shaped as to direct the inlet air along the most effective line onto the flat working areas of the fan blades. This idea is carried out throughout the entire fan. design and the shape of theinlet cone and of the streamlined shrou'dingj ring are also designed for the extremely smooth flow of the inlet air.

the larger, orlower', base II of the inlet cone. and is confined and converged by the converging The outside air enters, of course, the casing at walls oi the cone onto the curved inlet portions B of the tan blades. By having the innermost edges 2! of the inlet cone terminate, as is clearly shown by Fig. 15, Just underneath the streamlined ring II and in the area'iormed by the removal of the blade tips along the lines 20, all oi the inlet air is directed onto the curved inlet edges of the blade and is picked up by them and onto the working areas or the blades without recirculation oi the air into that space within the casing extending outside the ring 20.

The lower portion or the ring 2| is streamlined to provide the most elective air flow, without the production of air turbulence or eddy currents, from the inlet cone onto the curved inlet portions B o! the blades, and thence onto the straight working portions A of the blades. It was found that the provision of the streamlined ring not only increased the eiliciency of the fan, but decreased the noise that would be present were a straight enveloping ring employed.

The inlet cone, the streamlined enveloping ring, and the curved portions of the blades have been all carefully designed to cooperate to direct the inlet air along the most eil ective and'eflicient path so as to completely and most eiilciently load the working areas of the blades, and, as a result, a very ei'ilcient and compact tan is provided, which may be heavily loaded and whichmaybe operatedatveryhighspeeds. As an example, a tan according to this invention has been found to have an over-all eiliciency of 80%: was found to be much more compact than the ordinary type 0! fans previously developed .ior similar service; and was capable of being the Ian casing, and extends all of the way across.

the casing. except i'or a portion cut diagonally awayalong the line II, at the back portion of the wheel. It was tound tint with this cutaway portion, the cut-oii' sheet functioned just aseilleiently as acut-oi! sheet, and, at the same time, enabled the fan to. beoperated tar more quietly, due to the cessation of the series of jetlike impulses which ordinarily produce disturbi1: noises upon impact against the ordinary outo The remaining apparatus disclosed by the drawings is well known to those skilledin the art and soy its construction and operation will not be explained, since they form no part of the present invention.

While the inlet to the tan wheel. the curved inlet edges oi the tan blades, the streamlined shrouding ring, and the cut-oil sheet have been designed to cooperate for most ejilcient and quiet operation or a fan. according to this invention, it should be understood that one or more of these features may be omitted with the remaining features operating to give results more eilective andmoredesirablethanthatottheordinary tan. Each feature contributes its own electivemen, and this eflectiveness is, of course. accumulative when the various features, according to this invention, are used cooperatively.

Whereas one embodimentoi this-invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the details described. since many modialong said main portion, a shrouding ring around and attached to each of said blades at its periphery, a recessed portion in each of said blades and between it and the outermost edge of said ring, and an inlet casing attached to said main casing and terminating between the outermost edge of said ring and extending into said portions of said blades.

2. Centriiugal air moving apparatus, comprisinga main casing, a tan wheel having a plurality .of fan blades rotatable therein, each of said blades having a flat radial main working portion andacurvedinletportionshapedtodirectair axially along saidmain portion, ashrouding ring around and attached to each of said blades at its periphery, a recemed portion in each or said blades and between it and the outermost edge of said ring, and an inlet casim shapedto-iorm the irustrum oi a cone, its base diameter being greater than that of said wheel. and its smaller diameter being substantially equal to that of said wheel, said inlet casing terminating between the outermost edge of said ring andextending into said recessedportions of said blades.

' 3. Centrifugal air moving apparatus, comprising a main casing, a tan .wheel having a plurality of fan blades rotatable therein, each of said blades havingailatradialmainworkingportionanda curved inlet portion shaped to direct air axially along said main portion; a shmuding ring having a streamlined under portion around and attachedto each of said blades at its periphery; a I

portion in each ot said blades and between'it and the outermost edge oi. said-ring. and an inlet casing shaped to tom the irustrum ot a cone, its.

base diameter being greater than'that of said wheel, and its smaller diameter being substantially equal to that oi said wheel. said inlet casing terminating between the outermost edge oi said ring and extendinginto said recessed portions 01' said blades.

4. Aianblade adaptedtobesecured atitsbase 'ioarotaryshait,havingaradialmainworking portionwithsubstantiallyaplanesuriaceanda curved inlet portion, shaped to direct air axially along said main portion, all elements of said blade extending in lines radiating from the center line oisaid shaft, said curved portion having substantially a conoidal surface, said inlet portion and main working portion having substantially the same diameter whereby said inlet portion serves todirectairaxiallyalongthemtiresurtaceoi' said main working portion.

5. Aianbladeadaptedtobesecured atitsbase to a rotary shait, having a radial main working portion withsubstantially a plane surface and-a curved inlet portion shaped to direct air axially along said main portion, all elements of said blade extending substantially in lines radiating i'romthecenterlineoisaidshattandparallel 1 of said blade extending substantially in lines to every other line, said curved portion having inlet portion being substantially equal to that of said radial portion, a shroud ring attached to the curved portion of each of said blades at its periphery, a recessed portion in each of said curved portions of said blades and between it and the outermost edge of said ring,,and a converging inzp let casing for conveying air into said fan blades,

30 and a curved inlet portion shaped to direct air the smaller diameter of said casing being substantially equal to that of said blades, said 'inlet casing terminating between the outermost edge of said ring and extending into the recessed portions of said blades.

'l. Centrifugal air moving apparatus, comprising a main casing, a fan wheel having a plurality of fan blades rotatable therein, each of said blades having a flat radial main working portion said blades. 1

'8. Centrifugal air moving apparatus, comprising a. main easing, a fan wheelhaving a plurality, of fan blades rotatable therein, each of said blades having a curved inlet portion, a shrouding ring around and attached to each of said blades at its periphery, a recessed portion in each of said blades and between it and the outermost edge of said ring, and an inlet casing attached to said main casing and terminating between the outermost edge of said ring and extending into said recessed portions of said blades.

9. Centrifugal air moving apparatus, comprise ing a main casing,'a fan wheel having a plurality of fan blades rotatable therein, each of said blades having a curved inlet portion, a shrouding ring around each of said blades at its periphery, a recessed portion in eachof said blades and between it and the outermost edge of said ring, and an inlet casing attached to said main casing and terminating between the outermost edge of said ring and extending into said recessed portions of said blades.

10. A fan blade adapted to be secured at its ,base to a rotary shaft, having a substantially flat radial main working portion and a curved inlet portion shaped to direct air axially along said main portion, said curved portion having substantially the same width from base to tip, all

face and a curved inlet portion shaped to directair axially along said main portion. all elements radiating from the center line of said shaft, the

base portion of said inlet portion extending in substantially a straight line whichcoincides with an extension of the base line of said working portion, so that said curved portion has substantially a conoidal surface, said inlet portion and said main working portion having substantially the-same width from base to tip.

12. A fan blade adapted to be secured at its base to a rotary shaft, having a radial main working portion with substantially a plane surface and a curved inlet portion shaped to direct air axially along said main portion, said inlet portion and main working portion having substantially the same diameter to insure the directing by said inlet portion of entering air axially over the entire working surface of said main portion, said inlet portion having substantially the same width from base to tip and having substantially no curvature at its base and having a substantial degree of curvature at its tip, so as to have substantially a conoidal surface.

13. A fan blade adapted to be secured at its base to a rotary shaft, having a radial main working portion with substantially a plane surface and a curved inlet portion shaped to-direct air axially along said main portion, said inlet portion and main working .portion having substantially the same diameter to insure the directing by said inlet portion of entering air axially over the entire working surface of said main portion, said inlet portion having substantially the same width from base to tip and having substantially no curvature at its base and having a substantial degree of curvature at its tip, and

all elements of said blade extending substantially in lines radiating from the center line of said shaft, so that said curved portion has substantial- .ly a conoidal surface. I

' 14. A comldned propeller type and centrifugal type fan blade having a substantially flat main working surface and a curved inlet portion shaped to direct air axially along said main sur-- face, said curved portion having substantially a ameter whereby said curved portion directs air over the entire main working surface of said blade.

15. A combined propeller type and radial type fan blade having a substantially flat main working surface and a curved inlet portion shaped to direct air axially along said main surface, said curved portion having substantially a conoidal surface, said curved portion and said main surface having substantially the same diameter whereby said curved portion directs air over the entire main working surface of said blade.

16. A combined propeller type and centrifugal type fan blade adapted for use in a fan wheel having an axis about which it rotates, said blade having a substantially flat main working surface and a curved inlet portion, said inlet portion having substantially a conoidal surface, said curved portion and said main surface having substantially the same diameter whereby said curved portion'directs air over the entire main working surface of said blade, all elements of said blade extending substantially in lines radiating from said axis.

17. A combined propeller type and centrifugal type fan blade having a substantially flat main working surface and a curved inlet portion shaped to direct air axially along said main surface, said entiremain working surface oi. said blade, and

surface and a curved inlet portion shaped to direct air axially along said main surface, said curved portion having substantially a eonoidai surface, said curved portion and said main surface having substantially the same diameter whereby said curved portion directs air over the entire main working surface of said blade, and said curved portion having substantially the same width from base to tip.

19. A fan blade for use in a centrifugal fan,

having a substantially flat main working portion and a .curved inlet portion extending along substantiaily the entire air receiving portion of said main portion, said blade being recessed in the tip of said curved portion from its air entering edge to its point 'of joinder with said main portion for receiving a supporting ring.

20. A Ian wheel for a centrifugal fan comprising a plurality of radial type blades having substantiaily flat main working portions and curved inlet portions extending along substantially the entire air entering portions of said main portions,

said blades having recesses in the tips of their curved portions from their air entering edges to their points of ioinder with said main portions,

- and a shrouding ring having'a curved air guiding under portion in said recesses and attached to said curved portions.

21. A centrifugal fan comprising a casing, a plurality of radial type blades-having substan- 40 tially flat main working portions and having curved inlet portions extending along substantially the entire air enteringportions of said main portions, said blades having recesses in the tips of their curved portions from their air entering portions to their points of Joinder with said main portions, a supporting ring in said recesses, and

21A i'an blade for use in a centrifugal fan, having a substantially iiat main working portion I and a curved inlet portion extending along substantially the entire air receiving portion of said mainportion,saidbladebeingrecessedinthetip of said curved portion from its air entering edge to its point of ioindr with said main portion for receiving a supporting ring, said inlet portion having substantially a conoidal surface.

23. A centrifmal fan comprising a casing. a 10 plurality oi radial type blades having substantially flat main working portions and having curved inlet portions formed as surfaces of conoids extending along substantially the entire air entering portions of said main portions, said 15 blades having recesses in the tips of their curved portions from their air entering portions to their points ot-ioinder with said main portions, a supiporting ring in said recesses, and means forming an inlet passage into said casing, said passage 20 having an inner diameter substantially equal to the diameter of said ring and terminating adjacent the outermost edge of said ring.

24. Ann blade for use in a centrifugal fan,- having a substantially flat main working portion 25 and a curved inlet portion extending along substantially the entire air receiving portion of said main portion, said blade being recessed in the tip oi said curved portion from its air entering edge to its point of Joinder with said main portion roireceiving a supporting ring, said inlet portion having substantially a conoidal surface and having substantially the same width from base to tip.

25. A centrifugal fan comprlsinga casing,a plurality of radial type blades having substantially flat inainworking portions and having curved inlet portions extending along substantially the entire air entering portions ofsaid main portions, said blades having recesses in the tips of their curved portions from their air entering portions to their 40 points of Joinder with said main portions, a supporting ring in said recesses, and means forming an inlet passage into said casing, said passage having an inner diameter substantially equal to the diameter of said ring and terminating adjacent the outermost edge of said ring, said inlet portions having-substantially conoidal surfaces and having substantially the same width from baseto l 1 r HAROLD 1''. mean.- 

